Cutting tool insert

ABSTRACT

A cutting tool insert is disclosed. The disclosed cutting tool insert comprises: a supporting substrate extending in a first direction; and a cutting layer coupled to one surface of the supporting substrate and supported by the supporting substrate, wherein the one surface of the supporting substrate has an uplift part, which is uplifted in the first direction. The present invention can reduce a residual stress generated in a polycrystalline diamond compact.

TECHNICAL FIELD

The present invention relates to a cutting tool insert.

BACKGROUND ART

An insert for a cutting tool is coupled to a tool assembly used for anoil drilling operation or a cutting operation and is used for anexcavating operation of cutting down the bedrock and the like existingin the underground or a cutting operation of cutting metal or othermembers.

A plurality of inserts for the cutting tool is generally attached to thecutting tool.

Further, the insert for the cutting tool may include a supportingsubstrate shaped like a pillar, and a cutting layer formed at one end ofthe supporting substrate and formed of a super hard layer so as toperform a cutting function.

In this case, the cutting layer may include a polycrystalline diamondcompact, and the diamond compact is generally sintered under a hightemperature and high pressure condition, under which diamond particlesare crystallographically or thermodynamically stable.

DISCLOSURE Technical Problem

The present invention has been made in an effort to provide a cuttingtool insert, which is capable of decreasing residual stress generated ina crystalline diamond compact.

Other objects of the present invention are derivable by those skilled inthe art through an exemplary embodiment below.

Technical Solution

According to an exemplary embodiment of the present invention, there isprovided a cutting tool insert, including: a supporting substrateextended in a first direction; and a cutting layer coupled to onesurface of the supporting substrate and supported by the supportingsubstrate, in which the one surface of the supporting substrate isformed with an uplift part uplifted in the first direction.

The uplift part may include a center supporting part uplifted from acenter in the first direction, and a circumference supporting partuplifted between the center supporting part and an outer circumferentialsurface of the supporting substrate in the first direction.

The supporting substrate may have a cylindrical shape extended in thefirst direction, and the center supporting part may have a smallerdiameter (D2) than a diameter (D1) of the supporting substrate.

The circumference supporting part may be gradually uplifted from theouter circumferential surface of the supporting substrate to the centersupporting part.

An inclination (α) of the circumference supporting part based on asecond direction, which is perpendicular to the first direction, may be20° or less.

The center supporting part may be gradually uplifted from thecircumference supporting part to the center.

A curvature radius (r) of the center supporting part may be 37.5 mm orless.

A curvature radius (r) of the circumference supporting part may be 37.5mm or less.

A ratio of an area of the center supporting part to an area of theuplift part may be 0.45 to 0.8.

An upper surface of the center supporting part may be surface treated soas to have an unevenness structure.

The unevenness structure may be formed in a bilaterally symmetricstructure based on a center of the upper surface of the centersupporting part.

Advantageous Effect

According to the present invention, there is an advantage in that it ispossible to decrease residual stress generated in a crystalline diamondcompact.

DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view illustrating a cutting tool insertaccording to an exemplary embodiment of the present invention.

FIG. 2 is an exploded perspective view illustrating the cutting toolinsert according to the exemplary embodiment of the present invention.

FIG. 3 is a cross-sectional view taken along line AA of FIG. 1.

FIG. 4 is a diagram illustrating residual stress in a top portion and anoutside portion of a cutting layer according to an inclination angle ofa circumference supporting part according to the exemplary embodiment ofthe present invention.

FIG. 5 is a diagram illustrating residual stress in the top portion andthe outside portion of the cutting layer according to a curvature radiusof a center supporting part according to the exemplary embodiment of thepresent invention.

FIG. 6 is a diagram illustrating maximum residual stress according to aratio of an area of the center supporting part to an area of an upliftpart.

FIGS. 7A, 7B, and 7C are a top plan view, a front view, and across-sectional view of a supporting substrate 110′ according to anotherexemplary embodiment of the present invention, respectively.

BEST MODE

According to an exemplary embodiment of the present invention, there isprovided a cutting tool insert, including: a supporting substrateextended in a first direction; and a cutting layer coupled to onesurface of the supporting substrate and supported by the supportingsubstrate, in which the one surface of the supporting substrate isformed with an uplift part uplifted in the first direction

Mode for Carrying Out the Invention

The present invention may be variously modified and have variousexemplary embodiments, so that specific embodiments will be illustratedin the drawings and described in the detailed description. However, itis not intended to limit the present invention to the specificembodiments, and it will be appreciated that the present inventionincludes all modifications, equivalences, or substitutions included inthe spirit and the technical scope of the present invention. In thedescription of respective drawings, similar reference numerals designatesimilar elements.

Hereinafter, exemplary embodiments of the present invention will bedescribed in detail with reference to accompanying drawings.

FIG. 1 is a perspective view illustrating a cutting tool insert 100according to an exemplary embodiment of the present invention, and FIG.2 is an exploded perspective view illustrating the cutting tool insertaccording to the exemplary embodiment of the present invention.

FIG. 3 is a cross-sectional view taken along line AA of FIG. 1.

As illustrated in FIGS. 1 to 3, the cutting tool insert 100 according tothe exemplary embodiment of the present invention includes a supportingsubstrate 110 and a cutting layer 120.

The supporting substrate 110 according to the exemplary embodiment ofthe present invention may be formed in a pillar shape, for example, acylinder shape extended in a first direction. In this case, the firstdirection may mean an up direction of the supporting substrate 110 asillustrated in FIGS. 1 to 3.

The supporting substrate 110 may be formed of a carbide alloy includingtungsten (W), tantalum (Ta), vanadium (V), and titanium (Ti), and inthis case, cobalt (Co), iron (Fe), nickel (Ni), and the like may be usedas a binder for easily binding a pellet.

For example, the supporting substrate 110 may include a cobalt-basedtungsten carbide (WC-Co) alloy, and for a sintering process for formingthe supporting substrate, a sintering process may be performed byputting a cobalt-based tungsten carbide material into a mold.

The cutting layer 120 is formed on an upper surface of the supportingsubstrate 110.

In the present invention, for convenience of the description, it isassumed that the cutting layer 120 is formed on the upper surface of thesupporting substrate 110, but the cutting layer 120 may also be formedon a lower surface of the supporting substrate 110 according to adirection of the view.

The cutting layer 120 according to the exemplary embodiment of thepresent invention may include a basic material 122 and diamond particles124.

For example, the base material 122 may contain cobalt-based tungstencarbide (WC-Co), and the diamond particles 124 may be formed ofpolycrystalline diamond (PCD).

A sintering method is used for forming the cutting layer 120 on theupper surface of the supporting substrate 110, so that the sinteringprocess according to the exemplary embodiment of the present inventionwill be described in more detail.

First, a material for forming the cutting layer 120 is put into apredetermined mold in a powder form.

That is, cobalt-based tungsten carbide (WC-Co) powder for forming thebase material 122 and crystalline diamond particles for forming thediamond particles 124 are put.

In this case, a volume ratio of the diamond particles 124 in the cuttinglayer 120 may be ½ to ⅘. When the volume ratio of the diamond particles124 is less than ½, cutting efficiency is decreased. Further, the volumeratio of the diamond particles 124 is more than ⅘, the quantity of basematerial 122 interposed between the diamond particles 124 is decreased,and this causes deterioration of bonding force between the diamondparticles 124 and the base material 122, so that the diamond particles124 are easily separated from the cutting layer 120. Accordingly, thevolume ratio of the diamond particles 124 may be ½ to ⅘.

Next, the base material 122 and the diamond particles 124 are evenlydistributed by using a ball mill, an attrition mill, and the like.

Then, the supporting substrate 110 is put into the mold, into which thepowders are input, and the powders face the upper surface of thesupporting substrate 110 so that the cutting layer 120 is coupled to theupper surface of the supporting substrate 110.

In this case, the base material 122 may be distributed on a surface ofthe cutting layer 120 which is in contact with the upper surface of thesupporting substrate 110.

As described above, the supporting substrate 110 may contain thecarbide-based alloy (for example, a cobalt-based tungsten carbide), andthe base material 122 may also contain the cobalt-based tungstencarbide, so that the upper surface of the supporting substrate 110 andthe base material 122 contain the same component, and as a result,bonding force of the upper surface of the supporting substrate 110 andthe base material 122 may be further improved than bonding force ofother parts, that is, bonding force of the upper surface of thesupporting substrate 110 and the diamond particles 124.

In this case, bonding force of the supporting substrate 110 and thecutting layer 120 may also be improved by distributing only the basematerial 122 on the surface of the cutting layer 120 which is to bebonded to the upper surface of the supporting substrate 110.Accordingly, it is possible to prevent the supporting substrate and thecutting layer from being separated, thereby improving durability of thecutting tool insert.

Next, sintering is performed at a high temperature and high pressure sothat the supporting substrate 110 is coupled to the cutting layer 120.For example, a sintering process may be performed while maintaining upto a high temperature of about 1,300 to 1,500° C. and high pressure of 5to 7 GPa.

In order to maintain the high temperature and the high pressure, theprocess may be performed by sealing the mold, into which the supportingsubstrate and the cutting layer are put, with a large cell again, andafter the sintering process, the outer mold and the sealing cell areremoved, and then the supporting substrate and the cutting layer areprocessed and used.

According to a characteristic of the sintering process performed at thehigh temperature and the high pressure, the cutting tool insertaccompanies residual stress. That is, thermal coefficients of thesupporting substrate 110 and the cutting layer 120 are different, sothat residual stress is generated.

The residual stress generates cracks in an interface region and innersides of the supporting substrate and the cutting layer, thereby causingdeterioration of durability of the cutting tool insert.

According to the exemplary embodiment of the present invention, theresidual stress of the crystalline diamond compact, that is, the cuttinglayer 120, may be decreased, and hereinafter, this will be described inmore detail with reference to FIG. 3.

As illustrated in FIG. 3, an uplift part 112 uplifted in an upperdirection is formed on the upper surface of the supporting substrate 110according to the exemplary embodiment of the present invention. It canbe seen that when the cylindrical supporting substrate 110 is extendedin the first direction, the uplift part 112 is also uplifted in thefirst direction.

The uplift part 112 includes a center supporting part 1121 uplifted froma center in the up direction, and a circumference supporting part 1122uplifted between the center supporting part 1121 and an outercircumferential surface of the supporting substrate 110 in the updirection, and the circumference supporting part 1122 and the centersupporting part 1121 are uplifted toward the center.

First, the center supporting part 1121 is formed to have a smallerdiameter D2 than a diameter 1 of the supporting substrate 110 to supporta center part of the cutting layer 120.

An unevenness structure for improving bonding force with the cuttinglayer 120 may be applied to an upper surface of the center supportingpart 1121. For example, as illustrated in FIG. 3, the upper surface ofthe center supporting part may be surface-treated so that a plurality ofrecesses having a fan shape is formed along a circumference of thecenter supporting part.

In this case, the unevenness structure may have a bilaterally symmetricstructure based on a center of the upper surface of the centersupporting part so that bonding force with the cutting layer 120 isevenly improved throughout the entire upper surface of the centersupporting part 1121.

Further, the circumference supporting part 1122 is formed to begradually uplifted from the outer circumferential surface of thesupporting substrate 110 to the center supporting part 1121 to support acircumference part of the cutting layer 120.

The circumference supporting part 1122 has the gradually uplifted shape,so that the circumference supporting part 1122 is slantly formed, andherein, an inclination α of the circumference supporting part 1122 maybe 20° or less.

FIG. 4 illustrates residual stress in a top portion and an outsideportion of the cutting layer 120 according to an angle of an inclinationα of the circumference supporting part 1122 according to the exemplaryembodiment of the present invention.

Referring to FIG. 4, it can be seen that compared to a case where thecircumference supporting part 1122 is flat, when the inclination α is−10°, residual stress of the top portion and the outside portion isdecreased by 23.56% and 38.03%, respectively, when the inclination α is−15°, residual stress of the top portion and the outside portion isdecreased by 29.32% and 49.58%, respectively, and when the inclination αis −20°, residual stress of the top portion and the outside portion isdecreased by 35.10%, and 58.31%, respectively.

That is, the circumference supporting part 1122 is not formed to beflat, but is formed to be gradually uplifted from the outercircumferential surface of the supporting substrate 110 to the centersupporting part 1121, and thus, when the circumference supporting part1122 is formed to be slant by 20°, residual stress generated in the topportion and the outside portion of the cutting layer 120 may bedecreased up to 35.10% and 58.31%, respectively.

On the contrast to this, when the circumference supporting part 1122 isformed to be gradually lowered from the outer circumferential surface ofthe supporting substrate 110 to the center supporting part 1121, thatis, the circumference supporting part 1122 is formed higher than thecenter supporting part 1121, residual stress in the top portion and theoutside portion is increased by 11% and 61.69%, respectively, comparedto the case where the circumference supporting part 1122 is flat, sothat the case is not preferable.

In the meantime, when the circumference supporting part 1122 has aninclination larger than 20°, the material for forming the cutting layer120 is more consumed according to the increased inclination, and thediffusion is not properly performed during the sintering process, sothat the circumference supporting part 1122 may have an inclination of20° or less.

According to the exemplary embodiment of the present invention, thecenter supporting part 1121 may also be formed so as to be graduallyuplifted toward the center. That is, the center supporting part 1121 isformed to be gradually uplifted from the circumference supporting part1122 to the center to support the center portion of the cutting layer120.

The center supporting part 1121 has the gradually uplifted shape, sothat the center supporting part 1121 has a predetermined curvature, andin this case, a curvature radius r of the center supporting part 1121may be 37.5 mm or less.

FIG. 5 illustrates residual stress in a top portion and an outsideportion of the cutting layer 120 according to a curvature radius r ofthe center supporting part 1121 according to the exemplary embodiment ofthe present invention.

Referring to FIG. 5, it can be seen that compared to a case where thecenter supporting part 1121 is flat, when a curvature radius r is 40 mm,residual stress in the top portion and the outside portion of thecutting layer 120 is increased by 40.31% and 5.35%, respectively, butthe residual stress is sharply decreased until the curvature radius r is37.5 mm, and when the curvature radius r is 30 mm, residual stress inthe top portion and the outside portion of the cutting layer 120 isdecreased by 28.8% and 47.32%, respectively.

That is, the center supporting part 1121 is not flatly formed, but isformed to be gradually uplifted from the circumference supporting partto the center, and thus, when the center supporting part 1121 is formedto have a curvature radius r of 37.5 mm or less, residual stressgenerated in the top portion and the outside portion of the cuttinglayer 120 may be decreased up to 28.8% and 47.32%, respectively.

When a curvature radius r of the center supporting part 1121 is lessthan 30 mm, the material for forming the cutting layer 120 is moreconsumed according to the small curvature radius, and the diffusion isnot properly performed during the sintering process, so that the centersupporting part 1121 may have a curvature radius r of 30 mm or more.

In the meantime, for convenience of the description, the centersupporting part 1121 is discriminated from the circumference supportingpart 1122, but the center supporting part and the circumferencesupporting part are continuously formed to form one uplift part 110 onthe upper surface of the supporting substrate 110, and a curvatureradius of the circumference supporting part 1122 may be 37.5 mm or less.

The center supporting part 1121 has a curvature of 37.5 mm or less andthe circumference supporting part 1122 is formed to have an angle of 20°or less in order to decrease residual stress of the cutting layer 120 asdescribed above, so that an area ratio of the center supporting part1121 to the entire area of the uplifted part 110 may be drawn.

According to the exemplary embodiment of the present invention, an arearatio of the center supporting part 1121 to the entire area of theuplifted part 110 may be 0.45 to 0.8.

FIG. 6 illustrates maximum residual stress (a y-axis) according to anarea ratio (an x-axis) of the center supporting part to the area of theuplift part, and referring to FIG. 6, an area ratio of the centersupporting part is decreased within a range, in which an area ratio ofthe center supporting part is 0.45 to 0.8, so that maximum residualstress tends to also be decreased.

In this case, when the area ratio of the center supporting part to thearea of the uplift part is less than 0.45, the material for forming thecutting layer 120 is more consumed, and the diffusion is not properlyperformed during the sintering process, and when the area ratio of thecenter supporting part to the area of the uplift part is larger than0.8, there is difficulty in manufacturing the insert, so that the arearatio of the center supporting part to the area of the uplift part maybe 0.45 to 0.8.

In the meantime, the present invention has been described based on theexample, in which the predetermined inclination α angle according to theexemplary embodiment of the present invention is applied to thecircumference supporting part 1122, and simultaneously, the predeterminecurvature radius r according to the exemplary embodiment of the presentinvention is also applied to the center supporting part 1121, butaccording to another exemplary embodiment of the present invention, asillustrated in FIG. 7, a supporting substrate 110′, in which aninclination is applied only to a circumference supporting part 1122′,may also be taken.

FIGS. 7A, 7B, and 7C are a top plan view, a front view, and across-sectional view of the supporting substrate 110′ according toanother exemplary embodiment of the present invention, respectively, andas illustrated in FIGS. 7A, 7B, and 7C, an uplift part 112′ uplifted inan up direction may be formed on an upper surface of the supportingsubstrate 110′, and the uplift part 112′ may include a center supportingpart 1121′ uplifted from the center thereof in the up direction, and acircumference supporting part 1122′ uplifted in the up direction betweenthe center supporting part 1121′ and an outer circumferential surface ofthe supporting substrate 110′.

In this case, only the circumference supporting part 1122′ may be formedto be gradually uplifted from the outer circumferential surface of thesupporting substrate to the center supporting part, and the centersupporting part 1121′ may be formed in a flat shape, not a shapegradually uplifted from the circumference supporting part to the center.

In this case, it cannot be expected even a residual stress decreaseeffect according to an application of a predetermined curvature radius rto the center supporting part 1121′, but the inclination α angleaccording to the exemplary embodiment of the present invention may beapplied to the circumference supporting part 1122′, so that a residualstress decrease effect may be still expected.

In the meantime, the upper surface of the center supporting part 1121′of the supporting substrate according to another exemplary embodiment ofthe present invention may be surface treated so as to have an unevennessstructure for improving bonding force with a cutting layer 120.

A predetermined combteeth pattern may be formed on the upper surface ofthe center supporting part 1121′ by the surface treatment, and thecombteeth pattern may have a bilaterally symmetric structure based on acenter of the upper surface of the center supporting part 1121′ asillustrated in FIG. 7.

As described above, according to the present invention, there is anadvantage in that it is possible to decrease residual stress generatedto the cutting layer including crystalline diamond.

The specified matters and embodiments and drawings such as specificapparatus drawings of the present invention have been disclosed forillustrative purposes, but are not limited thereto, and those skilled inthe art will appreciate that various modifications, additions andsubstitutions are possible from the disclosure in the art to which thepresent invention belongs. The spirit of the present invention isdefined by the appended claims rather than by the description precedingthem, and all changes and modifications that fall within metes andbounds of the claims, or equivalents of such metes and bounds aretherefore intended to be embraced by the range of the spirit of thepresent invention.

1. A cutting tool insert, comprising: a supporting substrate extended ina first direction; and a cutting layer coupled to one surface of thesupporting substrate and supported by the supporting substrate, whereinthe one surface of the supporting substrate is formed with an upliftpart uplifted in the first direction.
 2. The cutting tool insert ofclaim 1, wherein the uplift part includes a center supporting partuplifted from a center in the first direction, and a circumferencesupporting part uplifted between the center supporting part and an outercircumferential surface of the supporting substrate in the firstdirection.
 3. The cutting tool insert of claim 2, wherein the supportingsubstrate has a cylindrical shape extended in the first direction, andthe center supporting part has a smaller diameter (D2) than a diameter(D1) of the supporting substrate.
 4. The cutting tool insert of claim 2,wherein the circumference supporting part is gradually uplifted from theouter circumferential surface of the supporting substrate to the centersupporting part.
 5. The cutting tool insert of claim 4, wherein aninclination (α) of the circumference supporting part based on a seconddirection, which is perpendicular to the first direction, is 20° orless.
 6. The cutting tool insert of claim 4, wherein the centersupporting part is gradually uplifted from the circumference supportingpart to the center.
 7. The cutting tool insert of claim 6, wherein acurvature radius (r) of the center supporting part is 37.5 mm or less.8. The cutting tool insert of claim 7, wherein a curvature radius (r) ofthe circumference supporting part is 37.5 mm or less.
 9. The cuttingtool insert of claim 7, wherein a ratio of an area of the centersupporting part to an area of the uplift part is 0.45 to 0.8.
 10. Thecutting tool insert of claim 6, wherein an upper surface of the centersupporting part is surface treated so as to have an unevennessstructure.
 11. The cutting tool insert of claim 10, wherein theunevenness structure is formed in a bilaterally symmetric structurebased on a center of the upper surface of the center supporting part.